This invention relates generally to an electromagnetic coupling such as a clutch or brake and, more particularly, to an armature assembly for such a coupling.
Newton U.S. Pat. No. 4,493,407 discloses a typical electromagnetic clutch in which an armature is connected to a driven hub by a mounting plate and is adapted to be frictionally coupled to a driving rotor when an electromagnet is energized to engage the clutch. When the clutch is engaged, the rotor acts through the armature and the mounting plate to rotate the driven hub.
In clutches of the type disclosed in the Newton patent, the armature is connected to the mounting plate by a series of leaf springs which couple the armature and mounting plate for rotation in unison while allowing the armature to move toward and away from the rotor when the electromagnet is energized and de-energized. Each spring usually is riveted at one end to the armature and at the other end to the mounting plate.
Torsional shock occurs when the clutch is first engaged and torsional spikes are created during steady state operation of the clutch. In order to dampen the torsional shock and to smooth the spikes, the clutch of the Newton patent utilizes an elastomeric spider between the mounting plate and the driven hub.
Clutches of the type disclosed in the Newton patent have experienced significant commercial success over the years. There exists a need, however, to reduce the cost, the complexity and the axial length of such a clutch. Because the armature assembly of the Newton clutch includes several components which must be separately fabricated and assembled, the clutch tends to be somewhat expensive. Moreover, the multiple components of the Newton armature assembly occupy significant space in an axial direction and thus the clutch does not lend itself for installation in extremely confined areas.